Jessica starts counting at 30, and she counts by threes. If 30 is the 1st number that Jessica counts. what is the 10th number that she counts?
Answer: What is the first number that she counts? $30$ What is the second number that she counts? $\begin{align*}&30 + 3 \\ &= 33\end{align*}$ What is the third number that she counts? $\begin{align*}&30 + 3 + 3 \\ &= 30 + (2 \times 3) \\ &= 36\end{align*}$ What is the 10th number that she counts? $\begin{align*}&30 + (9\times3) \\ &= 30 + 27 \\ &= 57\end{align*}$